In a recent study published in The Lancet Gastroenterology and Hepatology, researchers estimated the lifetime risk of gastrointestinal cancer and associated mortality.
Gastrointestinal cancers account for one-fourth of all cancer cases and a third of cancer deaths worldwide. The lifetime risk of incidence or death from gastrointestinal cancers is the cumulative probability of developing gastrointestinal cancers or associated mortality over a lifetime, accounting for demographic changes and competing risks from other causes of death.
Gastrointestinal cancer incidence and mortality rates have markedly varied over the past decades in countries across world regions. Estimating the lifetime risk can help understand the global profile of gastrointestinal cancers and inform future healthcare planning.
About the study
In the present study, researchers estimated the lifetime and age-conditional probabilities of incidence and death due to six gastrointestinal cancers in 185 countries. Data on new cases and deaths from esophageal, liver, colorectal, stomach, pancreas, and gallbladder cancers were obtained from the Global Cancer Observatory (GLOBOCAN) for 2020.
Population and all-cause mortality data were retrieved from the United Nations (UN) World Population Prospects 2019. Countries and world regions were classified into quartiles based on the Human Development Index (HDI). Lifetime risk was calculated using the adjusted for multiple primaries method.
Gastrointestinal cancer incidence, mortality, and all-cause mortality rates were used to estimate the lifetime risk by five-year age groups and sex. Risk estimates were computed at global, regional, and national levels and by HDI quartiles. Further, the lifetime risk of gastrointestinal cancers was compared with that of other common cancers.
The estimated lifetime incidence and mortality risks of gastrointestinal cancer were 8.2% and 6.1% in 2020 worldwide, respectively. The highest risk was observed for colorectal cancer at 38.5% (incidence) and 28.2% (death). Males generally had higher risk estimates than females. Besides, the lifetime risk of gastrointestinal cancers increased with HDI.
The lifetime risk of gastrointestinal cancers was 11.39% in countries with very high HDI and 2.61% in low-HDI countries; likewise, the lifetime risk of death from gastrointestinal cancers was 7.29% and 2.31%, respectively. Nevertheless, the lifetime risk of developing or dying from esophageal, liver, and stomach cancers was higher in countries with a high HDI than in countries with very high HDI.
The lifetime risk of death from esophageal and liver cancers was the highest in countries with low or medium HDI. The risk of having gastrointestinal cancers for the 0–40 age group was negligibly low worldwide, while it was 8.08% from 40 years onwards. There was a similar trend for the risk of death from gastrointestinal cancers.
The team noted discrepancies among countries within global regions by cancer type. Eastern Asia had the highest lifetime risks of developing (15%) or dying (11.7%) from gastrointestinal cancers. At the country level, Japan showed the highest risk of gastrointestinal cancers at 23.4%, while Mongolia had the highest risk of death (16.62%).
Eswatini had the lowest risk estimates. Eastern Asia had the highest risk of stomach, gallbladder, liver, and esophageal cancers, while Australia, Southern Europe, and New Zealand had the highest risks for colorectal cancer. Western Europe had the highest risk of pancreatic cancer. Middle Africa had the lowest risk for gallbladder and pancreatic cancers.
Central Asia had the lowest risk of liver cancer. The risk of stomach cancer was the lowest in Southern Africa. Colorectal and esophageal cancer risks were the lowest in Western Africa. Colorectal cancer had the highest lifetime incidence and mortality risks across 128 and 104 countries, respectively.
Compared to other cancers, the lifetime risk of gastrointestinal cancers (8.2%) was higher than that of breast cancer (5.9%), male genital cancers (4.88%), and respiratory cancers (3.87%). Similarly, the lifetime risk of death from gastrointestinal cancers (6.17%) was higher than that from breast cancers (2.13%) and respiratory cancers (3.21%).
Taken together, gastrointestinal cancers have a high lifetime mortality-to-incidence ratio (0.75). The risk estimates were higher in males compared to females. Colorectal cancer was the most predominant, with the highest lifetime risks in about 70% of countries. Risk estimates increased with HDI; specifically, countries with very high HDI showed over three-fold higher risks than low HDI countries.
The heterogeneity in estimates at regional and national levels suggests the need for targeted, context-specific cancer prevention strategies. National-level policies focusing on the education of the population, tailored screening for high-risk groups, and improvements in healthcare and treatment are needed to reduce the burden of gastrointestinal cancers.